Do we really need a remake of Paul Verhoeven’s 1990 sci-fi thriller Total Recall? No, but Hollywood is giving us one anyway, this time with Colin Farrell in the place of Arnold Schwarzenegger as the memory-challenged Douglas Quaid.

At the center of both movies is a company called Rekall that can implant fake memories and erase real ones with the help of a bulky, futuristic-looking machine. The original movie doesn’t explain how this happens, but that hasn’t stopped fans from speculating — something that carries extra weight when the fan is a professor specializing in both neuroscience and engineering.

“Here’s my crazy, mad-scientist idea,” says Dr. Charles Higgins, a neuromorphic engineer at the University of Arizona. “If you’re going to program memories all over the brain without doing anything invasive like opening up the skull and sticking all kinds of probes in, maybe what they injected was nanorobots — lots of them, maybe millions or billions of them.

“Those go to preprogrammed locations all over the brain, and the big machine we see in the movie is there to interact with the nanorobots, to tell them how to change synapses all over the brain in order to correspond with whatever the fake memory is going to be.”

We already know that people can be influenced to remember things that never happened, as in the famous “lost in the mall” experiment, conducted by psychologist Elizabeth Loftus, in which people were told four anecdotes that were supposedly from their childhood.

One of them, a story about being lost in the mall peppered with familiar details provided by family members, turned out to be false. No matter; 25% of the study participants said that they remembered it happening. The fact that memory is so malleable means that a Total Recall scenario isn’t completely infeasible.

“There is a theory about memory that says we don’t remember as much as we think we do, and what we actually remember are things that we rehearsed recently — things we thought about ourselves or told someone about,” says Higgins. “In that case, it might actually be easier to overwrite someone’s memory than we think, because there might not be that much information there in the first place.”

Higgins points out that while we’re getting better at building very tiny, nanoscale robots, we haven’t quite figured out how to make them smart enough to do anything useful — let alone reconfigure our brains in any significant way. Not to mention that it’ll be a while before we have a full understanding of how the human brain works.

But what about erasing memory? Total Recall isn’t the only movie to wrestle with the idea of what it means to erase one’s past. In Eternal Sunshine of the Spotless Mind, Jim Carrey’s character goes into a company called Lacuna to erase memories of a bad breakup.

While that might seem trite compared with erasing, say, evidence of an interplanetary conspiracy, a bad breakup is exactly the kind of emotional injury that the mind eventually represses so you can go on living a normal life. In the case of more serious events, sometimes the brain can completely block out the details of what happened.

“If you want to remove memory, trauma does that, so if you are in a terrible car accident you might not remember the car that hit you,” says Higgins. “Amnesia is pretty easy to come by, but selective amnesia is currently not doable.”

Forgetting is healthy. It’s when people can’t forget that life becomes difficult, which is why posttraumatic stress disorder is such a problem for the military. That’s also why scientists are working on ways to accomplish exactly what happens in movies like Total Recall and Eternal Sunshine of the Spotless Mind — the ability to erase specific memories.

Aside from hitting someone in the head with a blunt object every time something bad happens, is there any way to erase troubling memories?

The idea is that memories are rebuilt with fresh proteins every time you recall something, as opposed to being permanent files on a mental hard drive. This is important because it means that if you can inhibit the formation of these proteins while recalling something very specific — like a sexual assault or an attack on an army convoy — you could theoretically erase that memory.

So far, Nader’s research only pertains to rats, which forget to be afraid of a warning beep that precedes an electric shock. There’s some evidence, however, that it could work in humans too.

If the acts of remembering and forgetting are as vulnerable to interference as the research seems to show, the kind of memory manipulation suffered by Douglas Quaid in Total Recall doesn’t seem so far-fetched after all. It might, in other words, just be a matter of when — not if.

“How long will that be?” says Higgins. “Quite a while. Neither of us will be alive.”